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NetBeans internally uses the concept of a

<a href="http://top/org/openide/filesystems/doc-files/api.html"><em>virtual filesystem</em></a>.

This interface is used by all upper layers of NetBeans to read &amp;
write files, mount &amp; display directories, move and delete files, and
allow external compilation and execution to find libraries correctly.

<p>

NetBeans itself implements two filesystems: a <a
href="LocalFileSystem.html"><em>local</em> filesystem</a>,
which encapsulates access to the operating system's normal files; and
a <a href="JarFileSystem.html"><em>JAR filesystem</em></a>, which
allows users to mount Java Archive Files as if they were read-only
directories.

<p>

Using the <a href="http://top/org/openide/filesystems/doc-files/api.html"><b>Filesystems API</b></a>,
third parties may add support for access to file-like objects stored
in some different manner - for example, in a database or proprietary
object storage system. More commonly, module authors should use this
API whenever they need access to files; then their module should work
automatically with any filesystem supported by NetBeans.

<p>

Other capabilities provided by the Filesystems API include locking
files during write operations; listening for changes in a file's
status, so that another part of NetBeans may reflect that change; and
providing support for including the filesystem in the runtime class
path of an external compiler or executor.

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